DrWho Posted July 9, 2007 Share Posted July 9, 2007 Just thought y'all might enjoy these. We took these speakers out to Colter's carport driveway thing and ran some ground plane measurements at 3m. I'm not sure what the voltage was going into the speakers, but the SPL's should be relative. Only possible discrepancy would be with the 201's. Light Blue = HIP Dark Blue = HWL Brown/Gold = KP-201 Dark Red = KP-250 The first plot shows them all at once, and then the following pictures are showing each individual driver by themselves: Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 9, 2007 Author Share Posted July 9, 2007 For what it's worth, these measurements were taken with a 55ms gate time which corresponds to an 18Hz resolution. I smoothed the plot with all the speakers to 1/1 octave to make it easier to see, but all the other plots are not smoothed (in other words, this isn't a 1/3 octave smoothed graph like you would see in a magazine). So basically, above 100Hz this is a pretty good indication of a half-space anechoic response (since I was able to filter out the echos from the houses across the street). The 300Hz and 700Hz dips seem to correspond with standing waves inside the cabinets. I'm not sure why the KP-201 has the dip at 500Hz instead of 700Hz. Long story short, we lost the original KP-201 measurements and had to go back and retake them...so I wonder if the 700Hz and 500Hz dips might be related to a reflection in the environment. Either way, it is not something I would worry myself about. Quote Link to comment Share on other sites More sharing options...
pmsummer Posted July 9, 2007 Share Posted July 9, 2007 Cool! Thanks! Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 9, 2007 Author Share Posted July 9, 2007 Now that I think about it... Isn't 700Hz ish right around the crossover point? And by plaing the mic on the ground, you're going to get lobing from the non-aligned sources. Could it be that the 201 is crossing over lower? [] I guess the only way to find out is to run some curves on-axis with the squawker, or just measure the transfer function of the crossover... Quote Link to comment Share on other sites More sharing options...
jwc Posted July 9, 2007 Share Posted July 9, 2007 Nice info Mike Quote Link to comment Share on other sites More sharing options...
Islander Posted July 11, 2007 Share Posted July 11, 2007 Now that I think about it... Isn't 700Hz ish right around the crossover point? And by plaing the mic on the ground, you're going to get lobing from the non-aligned sources. Could it be that the 201 is crossing over lower? [] I guess the only way to find out is to run some curves on-axis with the squawker, or just measure the transfer function of the crossover... I'm no expert, but shouldn't the mic usually be on-axis with the squawker, unless you're testing/voicing the speaker for a listener who's lying on the floor? Quote Link to comment Share on other sites More sharing options...
Bill W. Posted July 11, 2007 Share Posted July 11, 2007 Mike- I think that 700hz void is due to the out- of phase condition created by the reversed polarity of the midrange and tweeter relative to the woofer on Heresys beginning with the type E crossover (for home use) as well as the crossovers used on the industrial versions. Earlier versions of the standard units had the drivers all wired with the same polarity. If you had a Heresy with a type D network or earlier, you would be looking at a rather different plot. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 11, 2007 Author Share Posted July 11, 2007 Now that I think about it... Isn't 700Hz ish right around the crossover point? And by plaing the mic on the ground, you're going to get lobing from the non-aligned sources. Could it be that the 201 is crossing over lower? [] I guess the only way to find out is to run some curves on-axis with the squawker, or just measure the transfer function of the crossover... I'm no expert, but shouldn't the mic usually be on-axis with the squawker, unless you're testing/voicing the speaker for a listener who's lying on the floor? The purpose of putting the mic on the ground is to keep any ground reflections from affecting the frequency response. If you're far enough way, you're inside the main lobe of all the drivers so it's not really an issue. The difference between the ground and 15 inches off the ground at 15 feet away is like 3/4" (pythagorean). The wavelength of 700Hz is 19 inches, which is huge compared to 3/4". Basically it shouldn't cause any noticeable phase cancellation. If we put the mic 15" off the ground, we would see a big dip in the response around 230Hz (1/4 wave boundary cancellation).If we wanted to get a more accurate "on-axis" response, it would be easier to tilt the speaker forward. But at 15 feet that's only a few degrees. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 11, 2007 Author Share Posted July 11, 2007 I think that 700hz void is due to the out- of phase condition created by the reversed polarity of the midrange and tweeter relative to the woofer on Heresys beginning with the type E crossover (for home use) as well as the crossovers used on the industrial versions. Earlier versions of the standard units had the drivers all wired with the same polarity. If you had a Heresy with a type D network or earlier, you would be looking at a rather different plot. Interesting, I think we will play around with the polarity the next time I'm at Colter's place. How deep is the K600? About 10 inches? 700Hz corresponds to about a 20" wavelength, so perhaps that dip is the result of the delayed signal coming from the squawker? And perhaps that's what the reversed polarity is trying to account for? I think we'll have to play around with this to see if we can't get rid of the dip. I have a feeling though that reversing the polarity is going to introduce a new dip at 800Hz and then the 700Hz dip will still be there, just not as deep. The only problem with that theory is that the KP-250 has the dips elsewhere. Quote Link to comment Share on other sites More sharing options...
Islander Posted July 11, 2007 Share Posted July 11, 2007 Now that I think about it... Isn't 700Hz ish right around the crossover point? And by plaing the mic on the ground, you're going to get lobing from the non-aligned sources. Could it be that the 201 is crossing over lower? [] I guess the only way to find out is to run some curves on-axis with the squawker, or just measure the transfer function of the crossover... I'm no expert, but shouldn't the mic usually be on-axis with the squawker, unless you're testing/voicing the speaker for a listener who's lying on the floor? The purpose of putting the mic on the ground is to keep any ground reflections from affecting the frequency response. If you're far enough way, you're inside the main lobe of all the drivers so it's not really an issue. The difference between the ground and 15 inches off the ground at 15 feet away is like 3/4" (pythagorean). The wavelength of 700Hz is 19 inches, which is huge compared to 3/4". Basically it shouldn't cause any noticeable phase cancellation. If we put the mic 15" off the ground, we would see a big dip in the response around 230Hz (1/4 wave boundary cancellation). If we wanted to get a more accurate "on-axis" response, it would be easier to tilt the speaker forward. But at 15 feet that's only a few degrees. That makes sense. Thanks for clearing that up, Mike. Quote Link to comment Share on other sites More sharing options...
Bill W. Posted July 11, 2007 Share Posted July 11, 2007 Mike, The Heresy uses a K-700, slightly shorter than the K-600. I don't know the crossover point on the KP-250 perhaps lower? There was a DFH bulletin from PWK in the mid 1970's about the change in crossover networks, I don't have the date available here. Personally, I feel the acoustic cancellation in the crossover region caused by the network change made the Heresys sound a little too thin in the lower midrange and favor the sound of a standard, not reversed polarity network in every A/B test I've heard with Heresys. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted July 12, 2007 Share Posted July 12, 2007 Doc, didn't we post on this before? Perhaps you just sent me the charts. Can we link to that thread here if it's available? I think the gang might be interested in our complete testing technique, in which we followed up the scientific measurement with some listening in the same environment. We used the Colter Comparator (A Niles box with Lpad volume controls) to blind switch between the four, first listening for overall preferences, then we used white noise to volume match them all and listened again. General results matched the measured (which is always a good thing). We noted that the sealed boxes had deeper bass, but the ported models with heavy duty woofers (HIP and KP250) had higher output. After volume balancing, the preference for the louder speakers gave way to those with more pleasing frequency response, which were the standard Heresy and the KP201, which is a standard Heresy in industrial wrap. Another interesting experiement we ran last time with the same setup was a combination of CA800SW sub, CA650T LF components only, swapping their networks, plugging various ports, then singular and in combo with KSB1.1 which I intended to use for a sub/sat outdoor setup. We're getting good at this stuff Doc, and we're getting good repeatable results that make sense. Good work! Who else but a true Klipsch Fan would think spending Sunday running outdoor ground plane tests was a FUN TIME? Michael Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted July 12, 2007 Share Posted July 12, 2007 Note on the Heresy test. The HIP was a very old, tired drummer's monitor. Ragged result might be a worn mid driver? I thought overall that we liked the KP201 the best, it was minty fresh, with the clear plastic still on the logo plate. Those are the ones in TN that I bought on eBay while at Dtels last Dec. Richard brought them up to me. They sound really sweet, particularly in the vocal range- look at that smooth curve in the mids compared to the other units! Doc, didn't we run some tests with BEC CT125 and K77, also K55V and K52 combos- the last time you were down here? Quote Link to comment Share on other sites More sharing options...
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